The Rev. Stehelin distilled Eisenmenger's German language original (2,100 pages) into his shorter, two-volume English translation.
The German language original, Entdecktes Judenthum, can be found on
archive.org and elsewhere.
The English 2-volume set was reprinted with a new introduction in 2006 by Michael A. Hoffman II / Revisionist
History.org and can be had from the usual mainstream book outlets.
The remarks by the commenter below appear quite inaccurate. His / her further remarks (from 2013) appear at
https://archive.org/details/Eisenmenger-Johann-Entdecktes-Judenthum-Zweyter-Theil
There are two scans of volume I of the English book on
archive.org but none of volume II despite it being freely available in print. Curiously the two scans of volume I differ at least in the respect that one ends at page 337 whereas the other has additional material on that page and ends with its content on page 338.
The page numbering of the original English print occasionally lapses but in creating his reprint of the 1748 edition reportedly Hoffman examined it against the 1742 printing and other sources.